奇數(shù)索引號可以通過以下示例來解釋：
document.getElementById('slides').onclick=handleSlideClick;
function handleSlideClick() {
let clickedSlide = event.target;
let clickedSlideIndex= Array.prototype.indexOf.call(clickedSlide.parentNode.childNodes, clickedSlide);
console.log(clickedSlide,clickedSlideIndex);
}
.slide {display:inline-block}
<div id="slides">
<div class="slide">one</div>
<div class="slide">two</div>
<div class="slide">three</div>
<div class="slide">four</div>
<div class="slide">five</div>
<div class="slide">six</div>
</div>
這里每個(gè)節(jié)點(diǎn)div.slide后面都有一個(gè) （“非換行空格”）節(jié)點(diǎn)。在索引計(jì)數(shù)中，這個(gè)小實(shí)體也很重要！如果你想避免這種情況發(fā)生，你可以替換.childNodes為.children：
document.getElementById('slides').onclick=handleSlideClick;
function handleSlideClick() {
let clickedSlide = event.target;
let clickedSlideIndex= Array.prototype.indexOf.call(clickedSlide.parentNode.children, clickedSlide);
console.log(clickedSlide,clickedSlideIndex);
}
.slide {display:inline-block}
<div id="slides">
<div class="slide">one</div>
<div class="slide">two</div>
<div class="slide">three</div>
<div class="slide">four</div>
<div class="slide">five</div>
<div class="slide">six</div>
</div>
